Fig. (4) Inducible expression of Cav-1 with significant reduction in basal level leakage expression. A Cav-1 and GFP expression cassette was constructed as depicted in the Figure by using 2 IRES and an RRE (LTR-IR-GFP-RRE-IR-Cav-1) sequences (A). This construct was cotransfected into 293T cells with or without Tat expression plasmid, pTatz. The expression levels of Cav-1 and GFP were examined by Western blot analysis. (B) Cav-1 expression from LTR-IR-GFP-RRE-IR-Cav-1 was examined for efficacy of inhibition of HIV replication by co-transfecting with NL4-3 and monitoring HIV replication by reverse transcriptase assay. (C) The XTT cell viability assay (Cell Signaling Technology, Danvers MA) was used to determine the nontoxicity and safety of LTR-IR-GFP-RRE-IR-Cav-1. Results are expressed as the means ± standard deviations (SD) from three determinations (P< 0.05).